Evidence is presented in support of the suggestion that the stria medullaris (SM) contains GABAergic afferents to the lateral habenula. It was found that the lateral (LHb) and medial (MHb) habenular nuclei differentially accumulate 3H-GABA and 3H-glutomate by a 4:1 ratio each, respectively. After SM lesion the uptake of GABA decreases in the LHb (62%) and glutamate uptake decreases in the MHb (50%). Experiments designed to chemically characterize the habenulo-raphe pathway have not supported prior electrophysiological studies which suggest that this is a GABAergic pathway.